Metex Shark Multi-Parameter Controllers & Analyzers - Manual (Page 14)

Section 3 - Electrical Connections and Setup Page 12
S H A R K
MULTI-PARAMETER CONTROLLER & ANALYZER USER’S MANUAL
Section 3 - Electrical Connections and Setup
3.8 RELAY A and B Setup
(LCD MENU SECTIONS - pH: 4.18 & 4.19, ORP: 5.17 & 5.18,
Conductivity: 6.18 & 6.19, Flow: 7.15 & 7.16)
Relay A & Relay B on the SHARK are SPDT dry
contact relays. They are configurable to operate in
response to rising or falling process values. Each
relay has independently adjustable on and off set-
points, cycle times, and fail-safe options.
The operator would use the control relays if the
device to be controlled is a simple on/off device.
For example a pump, solenoid valve, fan, or an
indicating light.
The control relays have 6 user configurable set-
tings:
DIRECTION: The relay can be set to control either
a rising or falling process. If for example the relay
is set to control a falling process, the ON set-point
must be set lower than the OFF set-point. If the
relay is set to control a falling process the SHARK
will not allow the RELAY OFF set point to be set
lower than the RELAY ON set-point. This rule will
also apply to a rising process.
RELAY ON set-point: This is the process value at
which the relay will energize. This value can be set
anywhere between 0-100% of the range.
RELAY OFF set-point: This is the process value at
which the relay will de-energize. Depending on the
direction for which the relay is configured, the
RELAY OFF set-point will only be setable in a lim-
ited range.
CYCLE ON time: To obtain a tighter process con-
trol, and limit over-shoot, the control relay can be
set with the cycling feature. This feature, if
enabled, will cause the control relay to cycle when
the process is between the RELAY ON set-point
and RELAY OFF set-point. The cycle on time is the
amount of time in seconds that the relay will be
energized. It can be set between 0 and 600 sec-
onds.
CYCLE OFF time: The CYCLE OFF time is the
amount of time in seconds that the relay will be de-
energized, it can be set between 0 and 600 sec-
onds. To disable the cycling feature set the cycle
off time to 0.
OVERFEED TIMER: The overfeed timer is
designed to help safeguard against a process or
instrumentation error causing one of the control
relays to remain energized for extended periods of
time.
When enabled, the overfeed timer will time out if
the control RELAY OFF set point is not reached
inside the overfeed time out. The control relays will
de-energize, the alarm relay will energize and an
LED will flash at the front.
FAILSAFE: The FAILSAFE feature is designed to
reverse the normal action of the control relay.
When the relay is set to FAILSAFE OFF the relay
will operate as a normal relay. When the relay is
de-energized the NO contacts are open and the
NC contacts are closed. Thus the device connect-
ed via the NO contacts will be off. When the relay
becomes energized the device will be on.
When the relay is set to FAILSAFE ON, the normal
action of the relay is reversed. Thus the NO con-
tacts act as the NC contact and the NC act as the
NO. The device connected to the NC contacts will
be energized when the RELAY ON set-point is
reached. The relay will be de-energized but
because it is acting in reverse the device will be
energized. When the RELAY OFF set-point is
reached the relay will energize and the device
connected to the NC contact will de-energize.
The purpose of the Fail Safe option is to have the
device turned on in the event of a power interrup-
tion.
The factory default for FAILSAFE is OFF.